The effect of Mo on nitrate reductase and nitrogenase activities as well as the growth and mineral nutrition of wheat inoculated with Azospirillum brasilense in greenhouse pot experiments under drought stress conditions was evaluated. Plant dry weight and total N-yield appeared to be drastically affected by the severe drought stress. This inhibition was associated with a decline in nitrate redu...

Nitrate uptake in Neurospora crassa has been investigated under various conditions of nitrogen nutrition by measuring the rate of disappearance of nitrate from the medium and by determining mycelial nitrate accumulation. The nitrate transport system is induced by either nitrate or nitrite, but is not present in mycelia grown on ammonia or Casamino Acids. The appearance of nitrate uptake activit...

Winter climate change has great potential to affect the functioning of terrestrial ecosystems. In particular, increased soil frost associated with reduced insulating snow cover may impact nitrogen (N) dynamics in cold ecosystems, but little is known about variability these effects among aggregates. A manipulation experiment was conducted investigate absence on N cycling within aggregates a spru...

Rate-limiting processes of catalysis by eukaryotic molybdenum-containing nitrate reductase (NaR, EC 1.7.1.1-3) were investigated using two viscosogens (glycerol and sucrose) and observing their impact on NAD(P)H:NaR activity of corn leaf NaR and recombinant Arabidopsis and yeast NaR. Holo-NaR has two "hinge" sequences between stably folded regions housing its internal electron carriers: 1) Hing...

We have compared the steady-state kinetics of wild-type nitrate reductase A and two mutant forms with altered beta subunits. To mimic conditions in vivo as closely as possible, we used analogues of the physiological quinols as electron donors and membranes with overexpressed nitrate reductase A in preference to a purified alpha beta gamma complex. With the wild-type enzyme both menadiol and dur...

Several aspects of the topography of the membrane-bound respiratory nitrate reductase (EC 1.7.99.4) of Escherichia coli have so far been explored (Kemp et al., 1975; Boxer & Clegg, 1975; Jones &Garland, 1977,1978; MacGregor &Christopher, 1978). Nevertheless, the location of the nitrate-binding site has not yet been positively identified. Garland et al. ( 1 9 7 5 ~ ) noted that the rate of passi...